Jennifer Lopez just checked a major box off her list and did it in full bombshell mode.

J.Lo made her Coachella debut Saturday night, popping up as a surprise guest during David Guetta's set. The crowd lost it when Guetta teased he had "invited a friend" and out came Lopez in a skintight, plunging bodysuit that showed off her insanely toned figure.

No easing into it either ... she hit the stage ready to go, tossing her sunglasses into the crowd and ripping off her feathered jacket like it was nothing.

The duo performed their new collab, "Save Me Tonight," live for the first time and the energy was through the roof as J.Lo strutted across the stage before embracing Guetta behind the DJ booth.

Her surprise set came just before Justin Bieber took over the main stage, making for a stacked night 2 lineup.

J.Lo's been grinding nonstop lately ... fresh off wrapping her Las Vegas residency last month.